Systems and methods for satellite communication

ABSTRACT

A system and method are disclosed which may include a plurality of ground stations operable to transmit and receive analog signal energy; at least one satellite in orbit around the earth and in communication with at least two ground stations, wherein the satellite comprises: a plurality of transponders, wherein at least two transponders are configured to communicate with at least two different transceiver stations; at least one routing mechanism for routing each analog data packet signal received at the satellite to a selected one of said at least two transponders based on a transmission frequency of each said analog data packet signal.

RELATED APPLICATIONS

This application is a continuation of PCT application Serial No.PCT/US08/063,853, filed May 16, 2008, entitled “SYSTEMS AND METHODS FORSATELLITE COMMUNICATION” [Attorney Docket 790-4-PCT], published as Pub.No. WO 2009/139778 on Nov. 19, 2009, the disclosure of which isincorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

The present invention relates in general to communication systems and inparticular to systems and methods for satellite based communication.

Satellite communication systems provide various benefits to consumers ofcommunication services such as for telephony, internet communications,television communications among others. Various satellite systems arecurrently available, which employ a wide variety of communicationoptions.

For instance, satellite communication systems provide a range of choicesfor routing signals that originate at earth-based customer terminals,get transmitted to satellites, and are then rebroadcast to othercustomer terminals. One option for directing signal traffic onboard asatellite is “bent-pipe” technology.

Bent pipe architecture is commonly employed in the satellite industry.The term “bent pipe” refers to a communication apparatus configured forre-broadcasting a signal without demodulating the signal. Thus, whenemploying this approach, the entire satellite communications pathremains in the analog domain.

One benefit of the bent-pipe approach is simplicity. Using the bent-pipeapproach, the same signal that is transmitted to the satellite isretransmitted back to an earth-based customer terminal. Retransmittingcommunication signals in this manner may be accomplished with simplecircuits having a small number of electronic components, which increasesreliability and reduces costs. Moreover, the reliability of thebent-pipe designs is enhanced by the fact that the circuits and circuitcomponents used in such designs operate in a well understood manner andhave established track records of successful operation dating back manyyears.

However, one drawback of this approach is that the bent-pipe design canbe inefficient at delivering data for Internet communication. This isbecause Internet data traffic is composed of many individual packetseach having their own destination addresses. A bent-pipe communicationapparatus has no means of reading the destination of a packet and thushas no decision-making capability regarding the routing of the packet.

Thus, determining the destination of a data packet requires that theanalog data of the packet be “demodulated” into logical 1 values andlogical 0 values, which demodulation is not performed by bent-pipecommunication apparatus. Thus, when using bent-pipe communicationequipment, all communication data are transmitted to a destination onthe Earth dictated by the configuration of the bent-pipe satellitecommunication apparatus. Thereafter, the transmitted data packets aredemodulated at the destination location. The IP (Internet Protocol)addresses of each packet may then be determined using the demodulateddata, thereby enabling the packets to be suitably re-routed to theirrespective destinations.

The packets are then transmitted from a ground terminal to one or moreselected satellites to enable delivering the packets their respectivedestinations. This process may require a “double hop” over thesatellite. Specifically, the data communication path may extend from asource to a satellite, then to a modem on the ground, then back to aselected satellite, and finally to the destination address.

The described communication trajectory can effectively double thecommunication latency (total round trip time from source to destinationand back again). For instance, when using a Geo-Synchronous (GEO)satellite, one full second or more may be needed for data to complete asingle round trip data path.

An additional drawback associated with the bent pipe design is that thetransponders on a satellite are dedicated to transmitting along aparticular path. This arrangement may be inefficient when only a portionof a transponder's bandwidth is needed for a given communication path.For example, a typical GEO satellite may have 50 transponders, with eachtransponder having a communication bandwidth of, for example, 36 MHz(Megahertz). The transponders can be “pointed” in any direction,including for instance to footprints on the Earth that are North, South,East, or West of a given satellite's location. Specifically, first andsecond groups of transponders on a given satellite could be arranged toconduct communication with two respective locations on the earth'ssurface.

A satellite operator can then sell links between physical locations. Forexample, a North-South bent-pipe satellite setup would involve using onetransponder to provide a communication link between the satellite and alocation on the Earth's surface to the south of the satellite. Anothertransponder on the satellite could be configured to provide a secondcommunication link between the satellite and a location on the Earth'ssurface to the north of the satellite. An example is considered in whichthe northern and southern locations correspond to Europe and southernAfrica, respectively. Thus, in this case, the full bandwidth of twotransponders will be employed for communication between these twospecific locations.

Using the above-described configuration, where only a portion of thebandwidth of a transponder is needed (such as, for instance, 20 MHz),the unused transponder bandwidth is useable only by a customer requiringcommunication bandwidth between the two locations served by thesatellite in question. This may lead to bandwidth either being wasted,or to being used inefficiently.

A case is considered in which a South African bank central office seekscommunication with various branch offices located in various locationsin southern Africa, where the various locations lack land-basedcommunication links to the central office. In this situation, thecentral office needs a satellite communication link coupling differentregions within southern Africa together. This coupling could be providedby a satellite having bent-pipe communication apparatus with differenttransponders having communication links with different respectivelocations within southern Africa, which may be referred to herein as“south-south” links. In a case such as this, the total communicationbandwidth required by the bank may correspond to less than the bandwidthof a single transponder. However, dedicating an entire transponder inthis manner to an application that needs only a portion of thetransponder's bandwidth is a costly and wasteful practice.

Moreover, in many cases, only north-south links are available. In thiscontext, “north-south links” refer to satellites having bent-pipecommunication apparatus including a first group of one or moretransponders in communication with one or more northern locations, and asecond group of one or more transponders in communication with one ormore southern locations. Thus, where only north-south links areavailable, the bank central office will generally communicate with itsbranch office by having its data transmitted from Africa to thesatellite, then to a ground location in Europe, where the data packetswill be demodulated. The data will then be sent back to the satellite,and from there be directed to the branch offices. However, as discussedearlier, this double-hop communication path produces considerablecommunication latency. Moreover, such a path also uses up valuablebandwidth on satellites configured to provide north-south links.

On-Board Processing

A well known alternative to a using bent-pipe communication apparatus,is to use an “onboard processor” on the satellite. Onboard processinggives the satellite the ability to read destination data for each packetand route the packets accordingly. If confronted with the fact patterndiscussed above, the satellite could be configured to have onetransponder for each of the North South, East, and West directions. Uponreceiving communication data, the satellite demodulates each packet,reads the destination information, and then suitably routes the packetto its destination based on the destination information. In this case,the onboard routing is able to direct the packet directly to itsdestination, and is therefore able to avoid the inefficiency incurred bythe “double hop” discussed above in connection with the bent-pipesatellite configuration. Thus, onboard processing is effective atefficiently using bandwidth and transponder capacity. Effectively, theonboard processor configuration provides a “router in the sky”.

However, onboard processing incurs disadvantages in the areas of cost,reliability, and obsolescence, as discussed in the following. Onboardprocessors for routing data use space-hardened semi-conductor deviceswhich require expensive, customized engineering. Moreover, operating theonboard processors requires a significant amount of additional power.The components needed to provide this additional power add significantweight and cost to the satellite in the form of additional solar panelsand batteries, among other devices.

The reliability of onboard processors is difficult to predict due to therelatively short history of such devices aboard satellites. Onboardprocessing requires semiconductor devices which undergo relatively rapidtechnological change. Accordingly, it is intrinsically difficult toprovide devices which are both fully up to date technologically andwhich also have a proven track record.

A typical satellite lifetime is between ten and fifteen years. Thus,during the life of the satellite, the available digital processingtechnology will have changed dramatically, and after the first few yearsthe technical features of the satellite's onboard processing system willhave become outdated.

Accordingly, there is a need in the art for a satellite communicationsystem that provides communication bandwidth efficiency both reliablyand at a reasonable cost.

SUMMARY OF THE INVENTION

According to one aspect, the invention provides a communication systemthat may include a plurality of ground stations operable to transmit andreceive analog signal energy; at least one satellite in orbit around theearth and in communication with at least two ground stations, whereinthe satellite may include a plurality of transponders, wherein at leasttwo transponders are configured to communicate with at least twodifferent communication devices; at least one routing mechanism forrouting an analog data packet signal received at the satellite to aselected one of the at least two transponders based on a transmissionfrequency of each analog data packet signal. Preferably, a transmissionpath of the analog data packet signal through the satellite includesonly analog equipment. Preferably, the routing mechanism comprises atleast one frequency divider. Preferably, the routing mechanism isoperable to select from a) a first transponder broadcasting toward afootprint on the earth in proximity to a current location of thesatellite; and b) a second transponder configured to communicate with agateway station, for rebroadcast of analog data packet signals routed bythe routing mechanism. Preferably, the first transponder broadcastingtoward the proximate footprint is operable to provide intra-regionbackhaul between transceiving devices within the footprint not havingland-based, wired connections disposed therebetween.

The system may further include a computing system in communication withat least one ground station, the computing system having a memory forstoring a data table containing a plurality of IP addresses and arespective plurality of transmission frequencies corresponding to the IPaddresses. Preferably, the computing system is operable to read IP(Internet Protocol) addresses of digital data packets received at theground station. Preferably, the computing system is operable to retrievea transmission frequency corresponding to the IP address of eachreceived digital data packet. Preferably, the at least one groundstation comprises a modem for converting the received digital datapackets into respective analog data packet signals. Preferably, eachcommunication device is one of: a) a ground station capable of bothreceiving and transmitting data; b) a satellite capable of bothreceiving and transmitting data; and c) a receiver.

According to another aspect, the invention provides a method for sendingdata within a satellite communications system that may include receivinga digital data packet at a first ground station within thecommunications system; converting the digital data packet into an analogsignal; establishing a magnitude of a selected physical characteristicof the analog packet signal as a function of a destination of thedigital data packet; transmitting the analog packet signal from thefirst ground station to a first satellite; routing the analog packetsignal to a given transponder aboard the first satellite based on themagnitude of the selected physical characteristic of the analog packetsignal; and transmitting the analog packet signal from the giventransponder to a transceiver station.

Preferably, the transceiver station is one of: a) a second satellite;and b) a ground station having a land-based connection with the digitaldata packet destination. Preferably, the physical characteristic isselected from the group consisting of: transmission frequency;amplitude; and signal shape. The method may further include identifyinga destination Internet Protocol (IP) address of the digital data packet;and wherein the establishing step comprises: establishing a transmissionfrequency for the analog packet signal based on the IP address of thedigital data packet. Preferably, the step of transmitting the analogpacket signal to the satellite comprises: transmitting the analog packetsignal using the established transmission frequency.

The method may further include performing the step of routing the analogpacket signal aboard the satellite using only analog equipment. Themethod may further include performing the step of routing the analogpacket signal aboard the satellite without demodulating the analogpacket signal. The method may further include performing the step ofrouting the analog packet signal using at least one frequency divider.Preferably, the step of transmitting the analog packet signal to thedestination of the digital data packet includes comprises one of:transmitting the analog packet signal to a gateway station; andtransmitting the analog packet signal out of a satellite transpondertoward a region on the earth including the first ground station, toeffect intra-region backhaul.

According to yet another aspect, the method may include providing atleast one satellite; receiving a signal at the satellite from a customersite; determining a transmission frequency of the customer signal;routing the customer signal to an output port of a transponder selectedaccording to the determined transmission frequency; and retransmittingthe customer signal from the selected transponder. The method mayfurther include prior to sending the signal to the satellite,determining a destination IP (Internet Protocol) address for the signal;and assigning a transmission frequency to the signal based on thedetermined destination IP address. Preferably, the routing stepcomprises: deploying a frequency divider having an input and a pluralityof outputs, wherein the frequency divider is operable to direct signalswithin a plurality of frequency ranges along a plurality of respectivesignal routing paths within the satellite. The method may furtherinclude configuring the frequency divider to associate a plurality oftransmission frequency ranges with a plurality of signal routing pathsemerging from the frequency divider. The method may further includecoordinating the association of the transmission frequency ranges withthe signal routing paths of the frequency divider with a correspondingassociation of frequency ranges to data transmission destinationsresident within a ground station transmission system.

According to another aspect, the method may include receiving a datapacket at a ground station within a satellite communication system, thedata packet including a destination IP (Internet Protocol) address;identifying the destination IP address of the data packet; selecting atransmission frequency channel for the data packet based on the IPaddress of the data packet;

transmitting the data packet to a satellite, of the satellitecommunication system, using the selected transmission frequency. Themethod may further include assigning a plurality of transmissionfrequencies to a plurality of respective transmission destinations. Themethod may further include modulating the data packet to provide ananalog signal indicative of the data packet, prior to the transmittingstep. The method may further include selecting a sub-channel, of theselected channel, for transmission of the data packet based on at leastone of: a) an identification of the ground station from which the datapacket is being transmitted; and b) an identification of a customer sitefrom which the data packet originated. The method may further includereceiving the data packet at the satellite; routing the data packetwithin the satellite in accordance with the transmission frequency ofthe data packet; and transmitting the data packet to a destinationtransceiver station within the satellite communication system.Preferably, the transceiver station is either a satellite or a groundstation.

Other aspects, features, advantages, etc. will become apparent to oneskilled in the art when the description of the preferred embodiments ofthe invention herein is taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purposes of illustrating the various aspects of the invention,the drawings illustrate some forms that are presently preferred, itbeing understood, however, that the invention is not limited to theprecise arrangements and instrumentalities shown in the drawings.

FIG. 1 is a block diagram of a communication system 100 including asatellite system in accordance with one or more embodiments of thepresent invention;

FIG. 2 is a block diagram of a portion of a communication system inaccordance with one or more embodiments of the present invention;

FIG. 2A is a block diagram of a portion of computing system that may bedeployed in communication with at least one ground station of the systemof FIG. 2;

FIG. 2B is a block diagram of a communication system in accordance withan embodiment of the present invention;

FIG. 3 is a block diagram of the electrical hardware aboard a satellitein accordance with one or more embodiments of the present invention;

FIG. 4A is a flow diagram of a series of steps that may be performed toconfigure a modem and ground station for transmitting and/or receivingdata in accordance with one or more embodiments of the presentinvention;

FIG. 4B is a flow diagram of a series of steps that may be performed toconfigure communication equipment on a satellite for receiving and/ortransmitting data in accordance with one or more embodiments of thepresent invention;

FIG. 5 is block diagram showing the location and condition of anexemplary data packet transmitted through a communication system inaccordance with one or more embodiments of the present invention;

FIG. 6 is a flow diagram of a method for routing a data packet through acommunication system in accordance with one or more embodiments of thepresent invention;

FIG. 7 is a block diagram showing a plurality of transponders on asatellite in accordance with one or more embodiments of the presentinvention;

FIG. 8 is a block diagram showing at least a portion of the signalrouting apparatus on a satellite configured in accordance with one ormore embodiments of the present invention;

FIG. 9 is a block diagram showing a modified version of the signalrouting apparatus of FIG. 8;

FIG. 10 is a schematic diagram of a satellite in communication with itsbroadcast region on the Earth, in accordance with one or moreembodiments of the present invention; and

FIG. 11 is a block diagram of a computer system adaptable for use withone or more embodiments of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following description, for purposes of explanation, specificnumbers, materials and configurations are set forth in order to providea thorough understanding of the invention. It will be apparent, however,to one having ordinary skill in the art that the invention may bepracticed without these specific details. In some instances, well-knownfeatures may be omitted or simplified so as not to obscure the presentinvention. Furthermore, reference in the specification to phrases suchas “one embodiment” or “an embodiment” means that a particular feature,structure or characteristic described in connection with the embodimentis included in at least one embodiment of the invention. The appearancesof phrases such as “in one embodiment” or “in an embodiment” in variousplaces in the specification do not necessarily all refer to the sameembodiment.

Those skilled in the art will appreciate the fact that antennas, whichmay include beamformers, and/or may include equipment for communicatingover optical links which communicate either with other satellites orwith ground stations, are reciprocal transducers which exhibit similarproperties in both transmission and reception modes. For example, theantenna patterns for both transmission and reception are generallyidentical and may exhibit approximately the same gain. For convenienceof explanation, descriptions are often made in terms of eithertransmission or reception of signals, on the understanding that thepertinent description applies to the other of the two possibleoperations. Thus, it is to be understood that the antennas of thedifferent embodiments described herein may pertain to either atransmission or reception mode of operation. Those of skill in the artwill also appreciate the fact that the frequencies received and/ortransmitted may be varied up or down in accordance with the intendedapplication of the system.

FIG. 1 is a block diagram of a communication system 100 including asatellite system 104 in accordance with one or more embodiments of thepresent invention. Communication system 100 may include ground stations106, satellite system 104, communication gateways 102, and communicationnetwork 108. The portions of system 100 identified above are describedfurther below.

Communication network 108 may be a ground based network that may includethe Internet. However, communication network 108 may refer to anycommunications network or system capable of employing a satellitecommunications system to enable communication between one or more groundstations 106 with a network 108 and/or with each other. Such systems mayinclude, either in place of or in addition to the Internet, telephonesystems (landline and/or wireless), radio communications (one-waybroadcast and/or two-way radio), television broadcasting, internationalwarning system broadcast (such as for weather emergencies or otherevent), and/or other communication systems.

Gateways 102 may serve as communication intermediaries between one ormore satellites and one or more ground-based communication networks.Herein, gateways 102 may serve as interfaces between communicationnetwork 108 and satellite system 104. Gateways 102 may include one ormore gateway stations or gateway terminals for receiving/transmittingdata for retransmission to satellite system 104 and/or communicationnetwork 108. Gateway stations 102 could be land-based and may provideany needed data communication routing and/or data format conversionneeded to enable communication between communication network 108 andsatellite system 104. For instance, gateway stations 102 may includecontrollers and/or other control means for controlling the location of adata communication path, such as by selecting one or more satellitesfrom among a plurality of satellites to conduct data communication withand/or selecting one or more transponders on one satellite ordistributed over a plurality of satellites for conducting datacommunication. In some respects, a gateway station 102 may be consideredto be a special-purpose ground station. However, in other embodiments,one or more gateways 102 may be satellites serving as intermediarytransceiving stations a) between a satellite and a ground station; b)between two satellites; and/or c) between two ground stations.

Herein, the terms “satellite system 104” and “satellites 104” are usedinterchangeably and generally refer to the totality of satellitesemployed as communication intermediaries in between gateway stations 102and ground stations 106. Satellite system 104 may include one or moresatellite constellations, wherein each constellation may include one ormore satellites. Thus, satellite system 104 may include any number ofsatellites from one up to any desired number. Each satellite 200 (FIG.2) of satellite system 104 may receive data from gateway 102 andretransmit such data either directly or via another satellite to one ormore specified ground stations 106 and/or to any other satellite 200within satellite system 104. Conversely, satellite system 104 mayreceive data from one or more ground stations 106 and retransmit thereceived data to gateway 102.

Ground stations 106 may be established in substantially permanentlyfixed locations and serve as a communications hub for networks ofcustomer sites as shown in FIG. 2. In other embodiments, ground stations106 may be mobile. For example, a ground station 106 may be implementedon a truck, trailer, or other vehicle capable of carrying and poweringantenna systems capable of communicating with one or more satellites.Alternatively, a mobile ground station could be a semi-permanentplatform, which is nevertheless moveable with suitable equipment whendesired. Mobile ground stations 106 could be useful, for example, forproviding information resources and communication to schools, hospitalsand the like, in circumstances where such institutions cannot affordpermanent ground stations at their respective locations.

Each ground station 106 may be connected to one or more subscribers,which may also be referred to as customer sites. Each subscriber mayinclude one or more user terminals. The nature and communicationbandwidth needs of the subscribers may vary widely. For instance, eachsubscriber may include one or more telephone companies, one or moreInternet service providers, one or more Internet cafés, one or moreindividual communications customers, and/or other form of communicationprovider such as a cable television provider, or any combination of theforegoing.

FIG. 1 depicts a configuration which may be employed by satellitesoperating at any desired orbit around the Earth, including GEO(Geo-Stationary Orbit), Medium Earth Orbit (MEO), Highly EllipticalOrbit (HEO), or Low Earth Orbit (LEO). GEO occurs at an altitude ofabout 36,000 kilometers (km). MEO refers to orbits at altitudes between2000 km and about 36,000 km above the surface of the Earth. LEO refersto orbits at altitudes lower than 2,000 km. Elliptical orbits refer toorbits in which the satellite altitude above the surface of the earthvaries as a function of the angular position of the satellite along itsorbit. HEO refers to elliptical orbits in which the distance of thesatellite from the earth varies substantially as a function of time, orotherwise stated with advancement of the satellite along its orbit.Moreover, system 100 may enable communication between different groundstations using a single satellite 200 of satellite system 104 as anintermediary between the ground stations. Alternatively, two or moresatellites 200 of satellite system 104 may communicate with respectiveground stations 106 that are in the respective ranges of the twosatellites. In this situation, gateway station 102 may communicate withthe two satellites to enable communication between the two satellites,and thus between the two ground stations 106.

Alternatively, two satellites may serve as successive intermediariesbetween two ground stations, where no single satellite has aline-of-sight connection with both of the ground stations at the sametime. Thus, the following sequences of links from a first ground stationto a second ground station could be implemented. In one embodiment, thelink could extend from a first ground station, to a satellite, to thesecond ground station, and then to a termination point at a customersite. In another embodiment, the link could extend from a first groundstation, to a first satellite, then to a second satellite, then to thesecond ground station, and then to a termination point at a customersite. In other embodiments, any number of satellites could be employedas intermediaries between ground stations in communication with oneanother. The above embodiments are discussed further in connection withFIGS. 2, 2A, and 2B.

FIG. 2 is a block diagram of a portion of a communication system 100 inaccordance with one or more embodiments of the present invention. Theportion of communication system 100 shown in FIG. 2 may includesatellite 200 and ground stations 106-a and 106-b on Earth 240. Sinceboth ground stations 106-a and 106-b are coupled to equivalent sets ofdevices, for the sake of brevity, only the devices coupled to groundstation 106-a are discussed below. Ground station 106-a may include dish202-a, modem 204-a, computing system 210, which is shown in greaterdetail in FIG. 2A. Moreover, ground station 106-a may be incommunication with customer sites CS1-a, CS2-a, and/or CS3-a. Groundstation 106-b may include and be in communication with a set of devicesparalleling that discussed above for ground station 106-a, as shown inFIG. 2. Dish 202-a may be any suitable telecommunications dish (alsoknown as a satellite dish). Dish 202-a may be configured to tracksatellite 200 as satellite 200 proceeds along an orbit above groundstation 106-a. While only one dish 202-a is shown, any number of dishesmay be deployed at ground station 106-a, or other ground station withincommunication system 100. In one embodiment, two dishes 202 may bedeployed at each ground station 106 which may operate in a round robinmanner, to enable ground station 106 to hand off communication withsatellite system (satellite constellation) 104 from one dish 202 toanother, in a round robin manner, as a first satellite 200 proceeds outof range of ground station 106, and a second satellite gradually entersthe range of ground station 106. In another embodiment, there may be twosatellites 200 between ground stations 106 a and 106 b, wherein thesignal path passes through the two satellites 200 and wherein the datatransmission means employed between the two satellites may includeoptical transmission and/or radio frequency transmission.

FIG. 2A is a block diagram of a portion of computing system 210 that maybe deployed at, and/or be in communication with, ground station 106-a ofFIG. 2. Computing system 210 may include all features needed to controlall parts of ground station 106-a, such as the computer components shownin FIG. 11. However, for the sake of brevity, only a subset of theportions of computing system 210 are shown in FIG. 2A. Computing system210 may include CPU 212 and memory 214. Data table 214 may be stored inmemory 214 and may store data associating destination IP addresses ofdigital data packets with respective transmission frequencies. For thesake of illustration, FIG. 2A shows a simplified version of data table216. Data table 216 includes simplified IP addresses 1001 and 1002,which correspond to customer site CS1-A and gateway station 102,respectively. It will be appreciated that in actual implementations, IPaddresses may be presented in any format suitable for the pertinentapplication. Moreover, any number of IP addresses and associatedtransmission frequencies and/or transmission frequency ranges may bestored in data table 216. While much of the description herein discusseslisting destination IP addresses in table 216, in other embodiments,address data stored in table 216 may include destination IP addresses,origination IP addresses, and/or the IP addresses one or moreintermediate points along a data communication path for a data packet.

In an embodiment, at ground station 106-a (and/or at other comparablyconfigured ground stations within communication system 100), computingsystem 210 may read the destination IP address of each digital datapacket 250, access table 216 within memory 214, and retrieve thetransmission frequency corresponding to the IP address read from thedigital data packet 250. Thereafter, ground station 106-a may transmitanalog data packet signal 260 using the transmission frequency retrievedfrom data table 216.

Data table 216 shows exemplary permissible frequency ranges that may beused for the respective IP addresses. Ground station 106-a preferablytransmits each packet signal 260 using a transmission frequency anywherewithin the transmission frequency range retrieved from data table 216for a particular IP address. In some embodiments, the transmissionfrequency ranges of table 216 may be sub-divided into still smallersegments based on the point of origin of each digital data packet 250.

The association of a frequency range, instead of merely a singlefrequency, with a given IP address, may be helpful in establishingfrequency division thresholds aboard satellite 200. This matter isdiscussed in greater detail in connection with FIGS. 8-9 herein.However, in brief, routing mechanisms, such as frequency dividers, maybe deployed within satellite 200 for routing analog packet signals 260therethrough. The transmission frequency ranges, such as those shown intable 216, corresponding to the respective IP addresses, may be employedto set thresholds in the frequency dividers in order to implementrouting decisions aboard satellite 200 that are consistent with the datain table 216 and that are consistent with the manner in whichtransmission frequencies were selected for each packet signal 250 priorto being transmitted from ground station 106-1 to satellite 200. Thus,for instance, in accordance with this embodiment, a packet signal 260received at satellite 200 having a transmission frequency of 19.011 GHz(see FIG. 2A) will preferably be routed by satellite 200 so as to bedirected to IP address 1002, which in this case corresponds to gatewaystation 102.

In one embodiment, satellite 200 may serve as an intermediary forcommunication between ground station 106-a and 106-b. Thus, for example,a digital data packet 250 may be transmitted from customer site CS1-a toground station 106-a. Suitable equipment (such as, but not limited to,modem 204-a and/or computing system 210) at ground station 106-a maythen read the destination IP address of the digital data packet 250 andselect a transmission frequency based on the destination IP address ofthat digital data packet 250. The digital data packet 250 may then bemodulated by modem 204-a to provide an analog data packet signal 260indicative of the digital data packet 250. The analog data packet signal260 may then be transmitted from ground station 106-a to satellite 200using the selected transmission frequency. Herein, the terms “packet” or“data packet” may be applied to both digital data packet 250 and analogdata packet signal 260.

Satellite 200 then preferably receives the data packet signal 260 andpreferably determines the transmission frequency of the received signal.Satellite 200 then preferably routes the data packet signal 260 to anoutput transponder (satellite dish) on satellite 200 that is selectedbased on the transmission frequency of the received data packet signal260. Satellite 200 then preferably retransmits the data packet signal260 out of the transponder along the intended path, which in this caseleads to ground station 106-b. It is assumed for this example that thedestination IP address identifies customer site CS1-b as its finaldestination. Thus, once the data packet signal 260 is received at groundstation 106-b, modem 204-b preferably demodulates the signal back intodigital data packet 250, and identifies the destination IP address.Ground station 106-b then preferably transmits the digital data packet250 to customer site CS1-b.

In the above example, satellite 200 serves as an intermediary betweenground stations 106-a and 106-b, each of which is coupled to multiplecustomer sites. However, satellite 200 may also be in communication withtwo or more ground-based communication stations of any suitable type.For instance, in other embodiments, satellite 200 may be an intermediarybetween a ground station and a gateway station, or between two gatewaystations. Moreover, each satellite 200 may communicate with one or moresatellites and/or with one or more ground stations.

FIG. 2B is a block diagram of a portion of a communication system inaccordance with an embodiment of the present invention. The portionshown in FIG. 2B includes ground stations 106-a and 106-b, satellite200, and satellites 120-a, and 120-b. For the sake of brevity, thedetails of ground stations 106-a and 106-b, discussed above inconnection with FIG. 2, are not repeated in this section. Thus, in thisembodiment, satellite system 104, shown generally in FIG. 1, may includesatellites 120 as well as satellites 200. Moreover, data packets beingtransmitted through communication system 100 may be transmitted throughtwo or more satellites within satellite system 104 as such packetsprogress from gateways 102 toward ground stations 106, or as suchpackets progress from ground stations 106 toward gateways 102.Transmitting a packet through a plurality of satellite “hops” in thismanner may be beneficial if a given satellite does not haveline-of-sight communication with two ground stations at the same time.

In this embodiment, the data communication link between ground stations106-a and 106-b may proceed from ground station 106-a to satellite 120-ato satellite 200, to satellite 120-b, and ultimately to ground station106-b. While the embodiment of FIG. 2B shows three satellites serving ascommunication intermediaries between ground stations 106-a and 106-b, itwill be appreciated fewer or more than three satellites could be used inthis manner. In one embodiment, satellites 120 may travel in a firstorbit, and satellites 200 may travel along a different orbit (i.e.differing in one or more of altitude, latitude, inclination, and soforth). However, in other embodiments, satellites 120 and 200 may travelwithin the same orbit.

Herein, a transceiver station may be either a ground station 106, or asatellite 120 or 200. Thus, a transceiver station may be anyintermediary communication device capable of receiving andretransmitting a digital data packet or a data packet signal. Moreover,in some embodiments, either ground stations 106 or satellites 200 maytransmit data to one or more communication devices that can only receivedata (receivers); and/or may receive data from one or more communicationdevices that only transmit data (transmitters). Herein, a communicationdevice is any device capable of receiving data and/or of transmittingdata. Thus, the present invention is not limited to employingcommunication devices that are capable of both transmitting andreceiving data.

FIG. 3 is a block diagram of the electrical hardware 300 aboard asatellite 200 in accordance with one or more embodiments of the presentinvention. Satellite hardware 300 may include processor 302, data pathcontrol 304, tracking antenna system 306, customer dishes 308, MUX 310,and/or amplification equipment 312.

Processor 302 may be a general processor having access to volatileand/or non-volatile memory. Processor 302 may be operable to coordinatethe flow of data among the gateway dishes and customer dishes 308. Datapath control 304 is preferably operable to control the flow of data fromvarious transponder inputs, along waveguides, and to various transponderoutputs within satellite 200. Data path control 304 may be implementedusing one or more MUX frequency splitters, by processor 302, by otherdevices, or using a combination of one or more of the foregoing.

Dual tracking antenna system 306 may be a communication interface inbetween gateway 102 (FIG. 1) and the remainder of the communicationequipment on satellite 200. Dual tracking system 202 may include two ormore mechanically or electronically steerable antennas and/orcommunication data conversion equipment for interfacing between gateway102 and communication equipment on satellite 200. In alternativeembodiments, a single gateway antenna may be employed. In oneembodiment, communication system 100 may be configured such thatsatellite 200 is always situated so as to be able to communicate with atleast one gateway 102 station. In other embodiments, a higher minimumnumber of communication paths between each satellite 200 and gatewaystations 102 may be maintained. Specifically, in some embodiments,communication system may be configured to ensure that one or moresatellites 200 within satellite system 104 maintain communication pathswith at least two gateway stations 102 at all times.

Customer dishes 308 are preferably any one of several types of satellitecommunication dishes capable of bi-directional communication with one ormore ground stations, one or more other satellites, and/or a combinationof ground stations and other satellites. Satellite 200 may include anynumber of customer dishes 308.

MUX/DEMUX 310 generally refers to equipment for combining signals from aplurality of sources onto a single waveguide and equipment forseparating out signals on a single waveguide onto a plurality ofdifferent waveguides. Particular features of these functions aredescribed in greater detail later in this document. Any neededcombination of separate multiplexers and/or demultiplexers may beemployed to fulfill the function of block 310.

Amplification 312 may be provided by one or more conventional radiofrequency (RF) amplifiers which are known in the art, and which could becomposed of either a traveling wave tube amplifier (twta) or solid statepower amplifier (sspa). Accordingly, a detailed description ofamplifiers that can perform the amplification 312 function is notprovided herein. One or a plurality of amplifiers may be provided aspart of hardware 300 of satellite 200.

FIG. 4A is a flow diagram of a series of steps 400 that may be performedto configure modem 204 and ground station 106 for transmitting data inaccordance with one or more embodiments of the present invention.

Frequency based routing may inexpensively implemented within a satellite200 by employing the transmission frequency of a data packet signal asan indicator of the destination of the data packet. This arrangementpreferably involves coordinating an association of destinations andtransmission frequencies at each ground station with a correspondingfrequency-destination association on each satellite within communicationsystem 100.

At step 402, a plurality of transmission frequency channels may beassigned to a plurality of respective transmission destinations.Preferably, the association of transmission frequencies, or frequencyranges in the form of “channels,” operates to encode destinationinformation for digital data packet 250 into the transmission frequencyused to transmit the data packet signal 260. The resulting transmissionfrequency is preferably later used by equipment aboard a satellite 200to suitably route the data packet signal 260.

Herein, the term “channel” corresponds to a frequency range of a carrierfrequency (transmission frequency) used for transmitting signals, suchas data packet signals 260. In some embodiments, the bandwidth of eachsuch transmission channel may be 10 MHz. However, in other embodiments,channel bandwidths may be lower than or greater than 10 MHz.

The degree of precision indicated by transmission using a given channelmay be established according to the needs of particular network. Forinstance, if the number of available transmission channels equals orexceeds the number of possible destination IP addresses, then onechannel may be assigned to each IP address without running out ofchannels. Alternatively, where the number destination IP addressesexceeds the number of available channels, channels of a given bandwidth,such as 10 MHz may each be assigned to a grouping of IP addresses. Thisgrouping of IP addresses may form part of a common network, may becoupled to a common ground station 106 (FIG. 2), may be located within adefined geographical region on the Earth, and/or have anothercommunication-related feature in common.

The above-described flexibility in the assignment of transmissionchannels to communication destinations is possible because, in mostembodiments, the practice of having the transmission frequency of a datapacket signal 260 serve as a proxy for transmission destination isbeneficial primarily for routing the data packet signal 260 through asatellite 200 and on to a ground station 106. Once the data packetsignal reaches a ground station 106, the signal may be demodulated intoa digital data packet 250. Thereafter, further routing of the datapacket 250 may be achieved by reading the destination IP address bitsincorporated into the data packet 250 using equipment designated forthis purpose that is readily available at Earth-based communicationhubs.

Thus, depending on the circumstances, the transmission frequency may beassociated with a range of data packet routing detail. The transmissionfrequency preferably specifies, at a minimum, which one of a number ofground stations 106 a transmitted data packet signal 260 will betransmitted to. However, the transmission frequency could specify moredetail, up to and including the final IP address of a computer that willreceive the data packet 250. In still other embodiments, where forinstance communication to a destination device passes through a numberof intermediate communication devices in between a destination groundstation and a final destination, the level of destination detailspecified by a transmission frequency may be such as to specify anydesired level of detail in between specifying the destination groundstation and the final data packet destination. More specifically, thetransmission frequency could specify an extent of transmission throughany desired number of the above-mentioned intermediate communicationdevices.

At step 404, the selection of transmission frequency ranges for thetransmission of data packets may be adjusted based the location fromwhich the data packet originates. The transmission frequency range maybe selected based on an identification of the ground station 106 fromwhich the data packet is being transmitted and/or an identification of acustomer site, such as CS1 (FIG. 2), from which the data packetoriginated. This may be desirable where a plurality of modems at aplurality of different respective ground stations all use the sametransmission channel.

In one or more embodiments, the frequency ranges associated with variousrespective transmission sources may be sub-channels of channels that areassociated with respective transmission destinations. Thus, an exampleis considered in which a channel “A” is employed to transmit to a givenground station 106-a. In this situation, individual modems serving assources for data destined for ground station 106-a may experience dataflow rates that are well within their operating limits. However, if thedata flow rates from the various modems are combined within satellite200 so as to be transmitted out of a single satellite transponder, thetransmission capability of the single satellite transponder could beexceeded.

In one embodiment, this congestion may be alleviated by allocatingportions of channel A, referred to herein as “sub-channels,” to modemsat different ground stations, that are all processing data packetsdestined for ground station 106-a. Thus, where four source groundstations GS1, GS2, GS3, and GS4 are directing data traffic to groundstation 106-a, four separate sub-channels of channel A (e.g. A1, A2, A3,and A4) could be assigned to the four transmitting ground stations GS1,GS2, GS3, and GS4, respectively. In one embodiment, the bandwidth ofchannel A could divided equally among the four sub-channels, therebyproviding each sub-channel with about 2.5 MHz of bandwidth.

Additionally or alternatively, in other embodiments, the available datacommunication throughput for a channel, such as channel A in the exampleabove, may be dynamically allocated among a plurality of modems based onthe data communication throughput needs of the various modems.

FIG. 4B is a flow diagram of a series 450 of steps that may be performedto configure communication equipment on a satellite 200 for transmittingdata in accordance with one or more embodiments of the presentinvention.

In an embodiment, frequency based routing may be implemented on one ormore satellites in a manner consistent with the above-discussedassignment of transmission frequencies to data transmission destinationsat the various ground stations 202. Preferably, the routing of datapacket signals through satellite 200 is established in coordination withthe association of transmission frequencies with destination IPaddresses conducted in step 402, at a ground station 106.

At step 452, on each satellite 200, connections may be establishedbetween frequency dividers and selected output transponders, usingsuitable equipment, such as waveguides. Continuing with the examplediscussed above, signals having a transmission frequency correspondingto the frequency range of channel A are preferably routed to an outputtransponder on satellite 200 that is configured to transmit to groundstation 106-a. In this manner, satellite 200 is preferably able to routea data packet signal by using the transmission frequency of the signalas a proxy for the destination IP address. Various options exist forimplementing this signal routing which will be discussed in greaterdetail in connection with FIGS. 8 and 9 of this application. In oneembodiment, establishing routing connections on satellite 200 as afunction of transmission frequency may be conducted once, uponconfiguration of satellite 200, and may remain in place for theoperating life of the satellite 200. However, in other embodiments,adjustable routing may be implemented such that control signals directedto an orbiting satellite may be operable to change the transmissiondestination of a signal having a transmission frequency within a givenfrequency range, such as, for example, between 18.5 GHz (Gigahertz) and18.6 GHz.

At step 454, bandwidth divisions may be implemented for one or morefrequency dividers aboard satellite 200. An example is considered inwhich a given frequency divider is set up to receive data packet signalsthat may be directed along one of two possible paths: a) back out to atransponder, or b) toward a gateway. For the sake of this example, thefrequency divider is assumed to receive signals having a transmissionfrequency range (bandwidth) of 20 MHz.

A bandwidth division for the frequency divider is preferably establishedbased on the expected data communication flow expected for the tworespective output paths from the divider. In most embodiments, onceestablished, the bandwidth division of the frequency divider will remainin effect indefinitely. However, where possible, an adjustable bandwidthdivision mechanism may be implemented that will enable alteration of thebandwidth division even after satellite 200 is placed in orbit. Thebandwidth division may depend on various factors including thecommunication requirements of the regions served by the satellite 200.For example, a satellite serving a region having limited wiredconnections on the ground may have a large proportion of its bandwidthallocated to retransmission of data out of the transponder pointing tothe point of origin. For example, in the above situation, 80% of thebandwidth could dedicated to retransmission out of the transponder, andthe remaining 20% could be directed to the gateway for eventual routingto one or more other regions on the Earth.

In some embodiments, different frequency dividers on a given satellite200 may have different bandwidth divisions implemented therein. Thus, asthe satellite 200 orbits over service regions having different needs,different transponder input-frequency divider paths may be activated toreceive data from the respective regions. In regions having an extensiveneed for data retransmission back down to the service area, theabove-described 80%-20% backhaul-gateway division could be implemented.In contrast, when the satellite is over areas not requiring much localretransmission, a different bandwidth allocation could be implemented.Thus, over this latter type of service area, an 20%-80% backhaul-gatewaydivision could be implemented, in which only 20% of the bandwidth isretransmitted back over the satellite-dish service area that thesatellite 200 is positioned over at a given moment in time.

The foregoing describes embodiments in which the transmission frequencyof a packet signal 260 is employed as a proxy for a destination IPaddress of the packet signal 260 to enable relatively simple, analogdevices aboard satellite 200 to conduct frequency-based routing withouthaving to demodulate packet signal 260 and read the IP address thereof.However, in other embodiments, characteristics of the analog packetsignal 260 other than frequency could be modified to enable signalrouting to be performed aboard satellite 200 without signaldemodulation. These other analog signal characteristics may include butare not limited to: amplitude and signal shape or other recognizablepattern. Thus, in such cases, one or more of these other characteristicscould be employed aboard satellite 200 as proxies for destination IPaddress either in addition to, or as an alternative to, the transmissionfrequency of analog packet signal 260.

FIG. 5 is block diagram showing the location and condition of anexemplary data packet 250 (FIG. 2) transmitted through a communicationsystem in accordance with one or more embodiments of the presentinvention. FIG. 6 is a flow diagram of a method for routing a datapacket through a communication system in accordance with one or moreembodiments of the present invention. FIGS. 5 and 6 are discussedtogether below.

FIG. 5 shows states of digital data packet 250 and analog data packetsignal 260 at various stages of the data transmission process. FIG. 5shows these states divided into three broad categories: those occurringat a ground transmission location 502, on a satellite 200 (location504), and a receiving ground station location 506.

At step 602, digital data packets 250 are formed at one or more customersites (state 510) and transmitted (step 604) to a designated groundstation, thereby providing digital data at ground station (state 512).At step 606, the destination IP address of packet 250 may be read. Atstep 608, the carrier frequency, which may also be referred to as the“transmission frequency” to be used to transmit data packet 250 may beestablished based on the destination IP address, as discussed inconnection with FIG. 4.

At step 610, data packet 250 may be converted into analog data (state514), thereby providing data packet signal 260 (FIG. 2). At step 612,the data packet signal 260 may be transmitted to satellite 200 using thefrequency selected in step 608, and be received at the satellite at step614, thereby providing analog data (state 516) at satellite 200.

Once within satellite 200, the data packet signal may be routed (step616) based on the transmission frequency thereof, thereby directing thedata packet signal 260 to a selected output transponder (state 518) ofsatellite 200. At step 618, data packet signal 260 may be transmittedout of the selected satellite transponder toward the destinationindicated by the transmission frequency of data packet signal 260. Atstep 620, the data packet signal 260 may be received at the receivingground station (state 520). At step 622, suitable equipment, such asmodem 204-b, may be employed to demodulate data packet signal 260 toprovide digital data packet 250 at the receiving ground station (state522). At step 624, the IP address of data packet 250 may be read tofurther route digital data packet 250 based on the destination IPaddress thereof. At step 626, digital data packet 250 may be routed toits final destination (state 524).

FIG. 7 is a block diagram showing a plurality of transponders onsatellite 200 in accordance with one or more embodiments of the presentinvention. In this embodiment, the transponders may both transmit andreceive wireless radio frequency communication.

Satellite 200 may include gateway transponders GW1 and GW2 forcommunication with two respective gateway stations on the ground (notshown). In other embodiments, satellite 200 could include fewer or morethan two gateway transponders. Satellite 200 may further include twelvetransponders for communication with ground stations that are incommunication with customers, including transponders C11, C12, C13, C14,C21, C22, C23, C24, C31, C32, C33, and C34. While twelve transpondersdirected to customer communication are shown in FIG. 7, fewer or morethan twelve transponders could be included within satellite 200.

In one embodiment, data received at an input of any of the transpondersof satellite 200 show in FIG. 7 may be routed so as to be output fromany of the fourteen transponders, including the transponder that thedata was received at. In other embodiments, to achieve greater economy,a more limited set of signal transmission routing options may be madeavailable within one or more satellites 200 within a constellation ofsuch satellites. This matter is discussed in greater detail inconnection with FIGS. 8 and 9.

FIG. 8 is a block diagram showing a portion of the signal routingapparatus 800 on satellite 200 configured in accordance with one or moreembodiments of the present invention. In one embodiment, portions ofapparatus 800 constitute one of several possible implementations of thefunctional blocks shown in FIG. 3. For the sake of brevity, hardwarecorresponding to various blocks of FIG. 3, such as processor 302 andamplification 312, are not shown in FIGS. 8 and 9.

For the sake of simplicity of illustration, signal routing apparatus 800shows one possible arrangement of signal connections for two customertransceivers 740,760 (which are also referred to herein as“transponders” and “dishes”) and one gateway transceiver 720. The dishesshown in FIG. 8: Gateway 1, and customer dishes C11 and C12, are asubset of those shown in FIG. 7. However, it will be apparent to thoseof skill in the art that the concepts shown in FIGS. 8 and 9 may beextended to all twelve customer dishes and the two gateway dishes shownin satellite 200 of FIG. 7, and in other embodiments, to any number ofgateway dishes and/or customer dishes.

FIG. 8 is directed to an embodiment in which data packet signals 260arriving at a receiver (denoted “Rx” in FIG. 8) of a gateway dish orcustomer dish are typically output along one of two possible directions.Specifically, the incoming signal may be directed back out of the dishit was received at, for intra-region backhaul, that is, back to theregion the data packet signal was transmitted from in the first place.This approach may be beneficially employed in regions in which variousground stations 106 are simultaneously in communication with a commonsatellite 200, but which are not in communication with one another viaground-based connections or where the cost of such terrestrialcommunications is excessive.

A second possible routing direction is toward a gateway station ofnetwork 100 that is in communication with a ground-based communicationnetwork, such as communication network 108 (FIG. 1). After beingtransmitted to a gateway station, a signal may be further routed to asuitable destination by other portions of communication network 100.

Signal routing apparatus 800 may include gateway 1 dish (GW1) 720,customer dish 1 (C11) 740, and customer dish 2 (C12) 760. Gateway dish720 may include input port Rx 722 which may be coupled to frequencydivider 726; and output port 724 which may be coupled to combiner 728.Customer dish 740 may include input port Rx 742 which may be coupled toswitch 750, which may in turn be coupled to frequency divider 746; andoutput port 744 which may be coupled to combiner 748. Customer dish 760may include input port Rx 762 which may be coupled to switch 770, whichmay in turn be coupled to frequency divider 766. Customer dish 760 mayfurther include output port 764 which may be coupled to combiner 768.

The satellite communication dishes 720, 740, and 760 may be conventionalsatellite dishes capable of bi-directional communication with Earthbased ground stations and/or with other satellites. Switches 750 and 770may be conventional waveguide switches. Combiners 728, 748, and 768 maybe conventional signal combiners.

Frequency dividers 726, 746, and 766 may be conventional frequencydividers, which may be OMUX frequency dividers. In some embodiments,each frequency divider may be configured during a setup phase of thesatellite to direct signals within a plurality of frequency ranges alonga plurality of respective signal routing directions. For example,frequency divider 746 could be configured to process signals havingtransmission frequencies between 19.0 GHz and 19.1 GHz. In thissituation, the frequency bandwidth handled by frequency divider is 0.1GHz, which may also be expressed as 100 MHz. In one embodiment,frequency divider 746 could be configured to direct signals havingtransmission frequencies greater than or equal to 19.00 GHz and lessthan 19.01 GHz toward combiner 748 for retransmission out of output port744 of customer dish 740. In this example, frequency divider 746 maydirect signals having transmission frequencies greater than or equal to19.01 GHz and less than or equal to 19.1 GHz toward combiner 728 fortransmission out of output port 724 of gateway dish 720. In this manner,frequency divider 746 effectively implements frequency based routing,using transmission frequency as a proxy for data packet signaldestination information, in accordance with one or more embodiments ofthe present invention.

In alternative embodiments, frequency divider 746 could be configured tohave a frequency division scheme that is adjustable while the satellite200 (that frequency divider 746 is located on) is in orbit. Suchadjustment would be preferably be accomplished remotely from a groundlocation by transmitting a specified set of radio frequency signals to asuitable control mechanism for adjusting the frequency divisionthreshold of frequency divider 746. While the above is directed to afrequency divider having two possible output paths, any number of outputpaths may be provided. The provision of three or more output paths fromfrequency divider 746 may be enabled using a single frequency dividerhaving three output paths and/or by providing a succession of frequencydividers, with two output paths each, having suitably configuredfrequency thresholds for implementing routing decisions.

In the following, the general operation of apparatus 800 in accordancewith one embodiment is discussed, followed by a more specific example.The apparatus 800 of FIG. 8 may be operable to receive signal energy,such as data packet signals, at a plurality of input ports, route thesignals based on the transmission frequencies thereof, perform anyneeded signal treatment, such as amplification, and then retransmit thesignals out of satellite 200 toward the destinations indicated by thetransmission frequency of each signal.

Signals may arrive at gateway dish 720 input port 722. Thereafter, theincoming signals may be routed at frequency divider 726 based on thetransmission frequencies of the respective signals. Thereafter, thesignals may be directed to combiner 748 and out of customer dish 740and/or to combiner 768 and out of customer dish 760, in accordance withthe signals' respective transmission frequencies. Each of combiners 728,748, and 768 is preferably operable to join signals having differingsources onto a single waveguide for transmission out of a single dish.

In one embodiment, signals arriving at customer dish 740 input 742 mayproceed to switch 750. Switch 750 may be set to either transfer allsignal energy to combiner 728 for retransmission out of gateway dish 720output port 724 or to direct all signal energy arriving thereat tofrequency divider 746 for division thereat in accordance with abandwidth division scheme in effect at frequency divider 746. Assumingthe signals are directed to frequency divider 746 from switch 750, afterthe frequency division, the signal energy may be directed towardcombiner 728 and/or combiner 748 in accordance with the frequencydivision scheme, for transmission out of gateway output 724 and/orcustomer dish 1 output 744.

Signals arriving at input port 762 of customer dish 760 may be processedin a manner parallel to that discussed above in connection with signalenergy arriving at customer dish 740. Since the routing circuit forprocessing signal energy input to customer dish 760 is essentially thesame as that used for customer dish 740, a detailed discussion of therouting of signal energy arriving at customer dish 760 is omitted forthe sake of brevity.

An example is considered in which signal energy including signals withtwo different transmission frequencies arrive at input port 742 ofcustomer dish 740: a) a first signal having a transmission frequency of19.005 GHz and b) a second signal having a transmission frequency of19.05 GHz. For this example, we resume the frequency division thresholddiscussed above for frequency divider 746. Specifically, signals withtransmission frequencies greater than or equal to 19.00 GHz and lessthan 19.01 GHz are directed to output port 744 of customer dish 740; andsignals with transmission frequencies greater than or equal to 19.01 GHzand less than or equal to 19.1 GHz are directed to combiner 728 fortransmission out of output port 724 of gateway dish 720.

Continuing with the example, both signals arrive at input port 742 ofcustomer dish 740. For the sake of this example, switch 750 is set todirect all signal energy toward frequency divider 746. Thus, bothsignals get transmitted to frequency divider 746. Frequency divider 746is preferably operable to direct the first signal, having a transmissionfrequency of 19.005 GHz, toward combiner 748 for retransmission out ofoutput port 744 of gateway dish 740, thereby providing intra-regionbackhaul to the region the signal was received from. Frequency divideris preferably also operable to direct the second signal, having atransmission frequency of 19.05 GHz, toward combiner 728 forretransmission out of output port 724 of gateway dish 720.

In the above manner, apparatus 800 may be operable to conductfrequency-based routing using frequency dividers, such as frequencydivider 746. Moreover, in this embodiment, when the apparatus 800 isemployed in coordination with the previously described assignment oftransmission frequencies as a function of data packet destination (atground station 106), the frequency based routing operation of apparatus800 effectively uses signal transmission frequency as a proxy fordestination information, and thereby effectively conducts destination IPaddress based routing without the expense, complexity, vulnerability,and risk of obsolescence associated with employing digital routingequipment aboard satellite 200.

FIG. 9 is a block diagram showing a modified version of the signalrouting apparatus 800 of FIG. 8. The embodiment of FIG. 9 is intended todemonstrate the routing flexibility available using one or moreembodiments of the present invention. Specifically, signal energyreceived at the input of a customer dish may be routed to one or moreother customer dishes in addition to, or as an alternative to, routingsuch received signal energy back out of the output port of the receivingdish or out of the output port 724 of the gateway 720.

The apparatus 800 of FIG. 9 includes two routing connections in additionto the equipment shown in FIG. 8. Specifically, the embodiment of FIG. 9may include link 902 and/or link 904 in addition to the otherconnections. In this embodiment, communication link 902 may extend fromfrequency divider 746 to combiner 768 to enable signal energy to betransmitted out of output port 764 of customer dish 760. Link 904 mayextend from frequency divider 766 to combiner 748, to enable signalenergy to be transmitted out of output port 744 of customer dish 740.

Links 902 and 904 are preferably operable to enable signals to be routedfrom the input of one customer dish to the output port of anothercustomer dish. The previously discussed example is resumed in thefollowing to illustrate the operation of this embodiment. In themodified example, signals (directed to frequency divider 746) withtransmission frequencies greater than or equal to 19.00 GHz and lessthan 19.01 GHz are directed to combiner 748 and then to output port 744of customer dish 740. Signals with transmission frequencies greater thanor equal to 19.01 GHz and less than or equal to 19.1 GHz are directed tocombiner 728 for transmission out of output port 724 of gateway dish720. And, signals with transmission frequencies between 19.1 GHz and19.2 GHz are directed to combiner 768 for transmission out of outputport 764 of customer dish 760. The above-described three-way division ofsignal energy directed into frequency divider 746 may be implementedusing a single frequency divider or by employing a succession of twofrequency dividers each having two outputs.

FIG. 10 is a schematic diagram of satellite 200 in communication withits broadcast area 1008 on the Earth 240, in accordance with one or moreembodiments of the present invention. FIG. 10 is provided to illustratethe utility of employing satellite 200 for backhaul communication fromground station 106 (at which a satellite dish is shown) to towers 1004and/or 1006 that are within the broadcast area 1008, on the Earth 240,of satellite 200. Broadcast area 1008 is shown bounded by dashed lines1008-a and 1008-b.

A case is considered in which ground station 106 possesses data intendedfor delivery to one of towers 1004 or 1006, but no ground-based, wiredconnection connects towers 1004 and 1006. In this case, ground station106 may transmit data to satellite 200. Preferably, the transmissionfrequency of the data packet signal sent to satellite 200 is properlyassociated with the intended destination of the data packet, both atground station 106 and within satellite 200. In accordance with theprinciples discussed in connection with FIGS. 8-9 of this application, adata packet signal 260 reaches satellite 200, and may be routed toward atransponder on satellite 200 that broadcasts to region 1008. Thereafter,one or both of towers 1004 and 1006 may receive the data packet signal250, demodulate the packet, and examine the destination IP address. Anytower (for example, tower 1004) that demodulates the packet and that isnot connected to the intended packet destination may simply discard thepacket. If, for example, tower 1006 demodulates the packet and discoversthat a customer connected (over a land-based connection) to tower 1006is the intended destination of the packet, tower 1006 may suitably routethe demodulated digital data packet 250 to the intended destinationusing conventional digital data transmission technology.

FIG. 11 is a block diagram of a computing system 1100 adaptable for usewith one or more embodiments of the present invention. For example oneor more portions of computing system 1100 may be employed to perform thefunctions of computing system 210 of FIGS. 2 and 2A, processor 302and/or data path control 304 of FIG. 3, of gateway 102 of FIG. 1, and/orof one or more processing entities within communication network 100 ofFIG. 1.

In one or more embodiments, central processing unit (CPU) 1102 may becoupled to bus 1104. In addition, bus 1104 may be coupled to randomaccess memory (RAM) 1106, read only memory (ROM) 1108, input/output(I/O) adapter 1110, communications adapter 1122, user interface adapter1106, and display adapter 1118.

In one or more embodiments, RAM 1106 and/or ROM 1108 may hold user data,system data, and/or programs. I/O adapter 1110 may connect storagedevices, such as hard drive 1112, a CD-ROM (not shown), or other massstorage device to computing system 1100. Communications adapter 1122 maycouple computing system 1100 to a local, wide-area, or Internet network1124. User interface adapter 1116 may couple user input devices, such askeyboard 1126 and/or pointing device 1114, to computing system 1100.Moreover, display adapter 1118 may be driven by CPU 1102 to control thedisplay on display device 1120. CPU 1102 may be any general purpose CPU.

It is noted that the methods and apparatus described thus far and/ordescribed later in this document may be achieved utilizing any of theknown technologies, such as standard digital circuitry, analogcircuitry, any of the known processors that are operable to executesoftware and/or firmware programs, programmable digital devices orsystems, programmable array logic devices, or any combination of theabove. One or more embodiments of the invention may also be embodied ina software program for storage in a suitable storage medium andexecution by a processing unit.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

1. A communication system comprising: a plurality of ground stationsoperable to transmit and receive analog signal energy; at least onesatellite in orbit around the earth and in communication with at leasttwo said ground stations, wherein the satellite comprises: a pluralityof transponders, wherein at least two said transponders are configuredto communicate with at least two different communication devices; and atleast one routing mechanism for routing an analog data packet signalreceived at the satellite to a selected one of said at least twotransponders based on a transmission frequency of each said analog datapacket signal.
 2. The communication system of claim 1 wherein atransmission path of said analog data packet signal through saidsatellite includes only analog equipment.
 3. The communication system ofclaim 1 wherein the routing mechanism comprises at least one frequencydivider.
 4. The communication system of claim 1 wherein the routingmechanism is operable to select from a) a first said transponderbroadcasting toward a footprint on the earth in proximity to a currentlocation of the satellite; and b) a second said transponder configuredto communicate with a gateway station, for rebroadcast of analog datapacket signals routed by said routing mechanism.
 5. The communicationsystem of claim 4 wherein said first transponder broadcasting towardsaid proximate footprint is operable to provide intra-region backhaulbetween transceiving devices within said footprint not havingland-based, wired connections disposed therebetween.
 6. Thecommunication system of claim 1 further comprising: a computing systemin communication with at least one said ground station, the computingsystem having a memory for storing a data table containing a pluralityof IP addresses and a respective plurality of transmission frequenciescorresponding to the IP addresses.
 7. The communication system of claim6 wherein the computing system is operable to read IP (InternetProtocol) addresses of digital data packets received at the groundstation.
 8. The communication system of claim 7 wherein the computingsystem is operable to retrieve a transmission frequency corresponding tothe IP address of each said received digital data packet.
 9. Thecommunication system of claim 8 wherein the at least one ground stationcomprises a modem for converting the received digital data packets intorespective analog data packet signals.
 10. The communication system ofclaim 1 wherein each said communication device is one of: a) a groundstation capable of both receiving and transmitting data; b) a satellitecapable of both receiving and transmitting data; and c) a receiver. 11.A method for sending data within a satellite communications system, themethod comprising: receiving a digital data packet at a first groundstation within the communications system; converting the digital datapacket into an analog signal; establishing a magnitude of a selectedphysical characteristic of the analog packet signal as a function of adestination of the digital data packet; transmitting the analog packetsignal from the first ground station to a first satellite; routing theanalog packet signal to a given transponder aboard the first satellitebased on the magnitude of the selected physical characteristic of theanalog packet signal; and transmitting the analog packet signal from thegiven transponder to a transceiver station.
 12. The method of claim 11wherein the transceiver station is one of: a) a second satellite; and b)a ground station having a land-based connection with the digital datapacket destination.
 13. The method of claim 11 wherein the physicalcharacteristic is selected from the group consisting of: transmissionfrequency; amplitude; and signal shape.
 14. The method of claim 11further comprising: identifying a destination Internet Protocol (IP)address of the digital data packet; and wherein the establishing stepcomprises: establishing a transmission frequency for the analog packetsignal based on the IP address of the digital data packet.
 15. Themethod of claim 14 wherein the step of transmitting the analog packetsignal to the satellite comprises: transmitting the analog packet signalusing the established transmission frequency.
 16. The method of claim 11further comprising: performing the step of routing the analog packetsignal aboard the satellite using only analog equipment.
 17. The methodof claim 11 further comprising: performing the step of routing theanalog packet signal aboard the satellite without demodulating theanalog packet signal.
 18. The method of claim 11 further comprising:performing the step of routing the analog packet signal using at leastone frequency divider.
 19. The method of claim 11 wherein the step oftransmitting the analog packet signal to the destination of the digitaldata packet comprises one of: transmitting the analog packet signal to agateway station; and transmitting the analog packet signal out of asatellite transponder toward a region on the earth including the firstground station, to effect intra-region backhaul.
 20. A method,comprising: providing at least one satellite; receiving a signal at thesatellite from a customer site; determining a transmission frequency ofthe customer signal; routing the customer signal to an output port of atransponder selected according to the determined transmission frequency;and retransmitting the customer signal from the selected transponder.21. The method of claim 20 further comprising: prior to sending thesignal to the satellite, determining a destination IP (InternetProtocol) address for the signal; and assigning a transmission frequencyto the signal based on the determined destination IP address.
 22. Themethod of claim 20 wherein the routing step comprises: deploying afrequency divider having an input and a plurality of outputs, whereinthe frequency divider is operable to direct signals within a pluralityof frequency ranges along a plurality of respective signal routing pathswithin the satellite.
 23. The method of claim 22 further comprising:configuring the frequency divider to associate a plurality oftransmission frequency ranges with a plurality of signal routing pathsemerging from the frequency divider.
 24. The method of claim 23 furthercomprising: coordinating the association of the transmission frequencyranges with the signal routing paths of the frequency divider with acorresponding association of frequency ranges to data transmissiondestinations resident within a ground station transmission system.
 25. Amethod comprising: receiving a data packet at a ground station within asatellite communication system, the data packet including a destinationIP (Internet Protocol) address; identifying the destination IP addressof the data packet; selecting a transmission frequency channel for thedata packet based on the IP address of the data packet; and transmittingthe data packet to a satellite, of the satellite communication system,using the selected transmission frequency.
 26. The method of claim 25further comprising: assigning a plurality of transmission frequencies toa plurality of respective transmission destinations.
 27. The method ofclaim 25 further comprising: modulating the data packet to provide ananalog signal indicative of the data packet, prior to the transmittingstep.
 28. The method of claim 25 further comprising: selecting asub-channel, of the selected channel, for transmission of the datapacket based on at least one of: a) an identification of the groundstation from which the data packet is being transmitted; and b) anidentification of a customer site from which the data packet originated.29. The method of claim 25 further comprising: receiving the data packetat the satellite; routing the data packet within the satellite inaccordance with the transmission frequency of the data packet; andtransmitting the data packet to a destination transceiver station withinthe satellite communication system.
 30. The method of claim 29 whereinthe transceiver station is either a satellite or a ground station.